6271

Simple command-line app I/O in Dart

Is there a way of taking single character (integer) keyboard inputs from the user and storing them to a variable in a Dart command-line app? I've tried something like:

Stream cmdLine = stdin
  .transform(new StringDecoder())
  .transform(new LineTransformer());

StreamSubscription cmdSubscription = cmdLine.listen(
  (line) => (choice = line);
  cmdSubscription.cancel(););


In an attempt to store a keyboard input into the variable 'choice' and many slight variations of this code but can't get it to work.

Answer1:

Currently you can only read a whole line at a time - i.e. once enter is pressed.

Star this issue.

<strong>Updated:</strong>

The readLine() function waits for a line of input from a user and returns it as a string.

import 'dart:async';
import 'dart:io';

main() {
    print('1 + 1 = ...');
    readLine().then((line) {
        print(line.trim() == '2' ? 'Yup!' : 'Nope :(');
    });
}

Future<String> readLine() {
    var completer = new Completer<String>();

    var input = stdin
        .transform(new StringDecoder())
        .transform(new LineTransformer());

    var subs;
    subs = input.listen((line) {
        completer.complete(line);
        subs.cancel();
    });

    return completer.future;
}

    

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